To solve this problem we can use proportion, but first its nice to transform our fraction into improper fraction, so
[tex]83 \frac{7}{10}= \frac{837}{10} [/tex]
and
[tex]2 \frac{1}{4}= \frac{9}{4} [/tex]
Now we can make proportion
[tex] \frac{837}{10} [/tex]--------------------------[tex] \frac{9}{4} [/tex] of fuel
x-----------------------------[tex]1[/tex]
Now we can cross multiply
[tex]x= \frac{ \frac{837}{10} }{ \frac{9}{4} }= \frac{837}{10}* \frac{4}{9} = \frac{3348}{90}=37.2 [/tex] - its the result